Safety appliances including but not limited to ladder rungs, hand holds and walkways generally must be attached to railway freight cars with fasteners because rules of the Association of American Railroads require that such safety appliances not be welded to the car. If such a safety appliance is to be mounted on a surface of the car where there is no access behind the mounting surface, the appliance must be mounted by means of a blind hole formed in the mounting surface. Such blind hole mounting is required for mounting safety appliances in many places on the sides and ends of the car.
Previously blind hole mounting of safety appliances on railways cars has been done by providing one or more vertically extending key slots in the mounting surface with the bolt head receiving portion of the slot above the key portion of the slot. The size of the head receiving portion of such key hole slots are larger than the transverse dimensions of the bolt head and the head of the bolt is inserted perpendicularly into the head portion of the slot and moved into the key portion so that the head is prevented from removal from the slot by the key portion of the slot. A shoulder formed on the shank portion of the bolt prevents the bolt from dropping through the key portion of the slot. The shoulder however is not sufficiently large to prevent the bolt from dropping through the bolt head receiving portion of slot during initial insertion of the bolt. An elongated metallic washer having a dimple is applied to the flat neck bolt. The dimple in the elongated metallic washer engages the head portion of the key slot to prevent the bolt from coming out of the slot by vertical movement. The bolt has a flat neck and a safety appliance or a safety appliance support is provided with openings through which the shank of the flat neck bolt passes and threaded nuts hold the appliance or appliance support on the shank. Since the bolt has a flat neck the key portion of the slot prevents the bolt from rotating when a fastening nut is applied. To ensure that the flat neck bolts will not vibrate off, a welder heats the shank portion of the flat neck bolt and then the shank is deformed to hold the nut in place.
The elongated metallic washers and the flat neck bolts are often difficult to obtain. When they are available they tend to be expensive. The heating and shank deformation steps require expensive welder time for each blind hole fastener applied to the car.
While the elongated metallic washer covers the mounting slot, it does not provide a seal sufficient to prevent significant amounts of water and other material from entering the slot and thus enter the space behind the mounting surface. In some portions of the car such water or material will automatically drain, and a seal may not be required. However, in other portions drainage is not provided and a seal for the slot is needed.